Christopher Clark graphed the peak levels of and RMS levels of three hit songs a year over the past three decades. This image links to a PDF of his full poster, "A Visual History Of Loudness." Christopher Clark hide caption

itoggle caption Christopher Clark

Inside Atlanta's new air traffic control tower, a dozen controllers separate arriving and departing planes. Jim Burress for NPR hide caption

itoggle caption Jim Burress for NPR

Even the pope has gotten into social networking on the Pope2You Web site featuring a photograph of Pope Benedict XVI on the home page. The site translates its content into English, French, Spanish, German and Italian. Pier Paolo Cito/AP hide caption

itoggle caption Pier Paolo Cito/AP
John G. Mabanglo/AFP/Getty Images